1. Field of the Invention
The present invention generally relates to a barcode symbol reading system and, more particularly, to a barcode symbol reading apparatus capable of shortening the time required for reading and decoding by eliminating an unnecessary reading operation in a barcode symbol reading system for reading a barcode symbol from a recording medium on which a barcode symbol is recorded.
2. Description of the Related Art
In recent years, barcode symbols are adopted in many countries, and the number of types of barcode symbols is very large. As typical barcode symbols, JAN/UPC/EAN codes, ITF (interleaved 2 of 5) codes, CODE39, NW-7 codes, CODE128, and the like are known. Recently, in order to meet requirements for an increase in information volume and a decrease in adhesion area, two-dimensional barcode symbols which have a large information amount and a high recording density have begun to be proposed. As two-dimensional barcode symbols, CODE16K, CODE49, PDF417, DATA CODE, VERI CODE, SOFT STRIP, and the like are known. Of these barcode symbols, the CODE16K, CODE49, and PDF417 are called multiple-row barcode symbols since they have a pattern obtained by stacking conventional barcode symbols in multiple rows.
On the other hand, many types of apparatuses for reading the JAN/UPC/EAN codes, ITF (Interleaved 2 of 5) codes, CODE39, NW-7 codes, CODE128, and the like (called one-dimensional barcode symbols in contrast to the two-dimensional barcode symbols) have been proposed. As typical apparatuses, pen type, touch type, and laser type apparatuses are known. On the other hand, the number of types of apparatuses for reading the two-dimensional barcode symbols is small, and the reading technique therefor is not established yet.
However, the basic principle of a method of reading the two-dimensional barcode symbols is substantially the same as that of a conventional method of reading the one-dimensional barcode symbols. More specifically, light is irradiated from a light source onto a barcode symbol, light reflected by the barcode symbol is received by a light-receiving element in a reading apparatus, and the received light is converted into an electrical signal. The converted electrical signal is decoded by an electrical circuit constituted by a microcomputer, and the like, thus reading the barcode symbol.
In recent years, card-shaped media printed or adhered with barcode symbols such as a magnetic card, IC card, optical card, and the like, have begun to be used. It is expected that such barcode cards be quickly spread due to their high portability.
In general, a reading apparatus for a magnetic card or the like is called a swipe type card reader since it reads the recorded contents when a card is slid along a slit by an operator. Also, a so-called time card type apparatus which reads the contents when a card is inserted/removed into/from an insertion port of a card reader by an operator is known, and is generally called a dip type card reader. These swipe and dip type card readers are compact and inexpensive. For this reason, an apparatus for reading a card printed or adhered with a two-dimensional barcode symbol is also required to be compact and inexpensive.
As an apparatus for reading a barcode symbol printed or adhered onto a card-shaped medium, an apparatus described in Japanese Patent Application No. 5-57229 (corresponding to Japanese Patent KOKAI Publication No. 6-266881) by the same inventor that of the present invention is available. The barcode symbol reading apparatus described in Japanese Patent Application No. 5-57229 reads the contents of a barcode symbol using a linear sensor (1DCCD) array. This patent application describes in detail the swipe and dip type card readers, i.e., a method of converting a signal obtained from the linear sensor (1DCCD) array into a width data string by proper processing, and efficiently storing the converted width data string in a FIFO memory.
A card is swiped by an operator, and the swipe speed is not constant. Some operators swipe the card at high speed, while other operators swipe the card at low speed.
When a card is swiped at low speed, the number of scan times per row of a barcode symbol increases, and a large amount of an extra width data string is stored in the FIFO memory. Therefore, since the information amount to be processed increases, the processing time is prolonged, resulting in an unnecessarily long reading time of a barcode symbol. The barcode symbol reading apparatus described in Japanese Patent Application No. 5-57229 does not take any countermeasure against this problem.
As a barcode reader for reading and decoding a barcode symbol, various types of apparatuses are known. As reading means in these barcode readers, scanning means using a laser, image pickup means using a line or area sensor, and the like are popularly used.
More specifically, in the laser method, a laser beam spot is scanned on a barcode symbol, and the intensity of light reflected from a portion in the spot is time-serially detected. In the line or area sensor, a barcode symbol image is formed on the sensor using an optical system, and light amount information detected by elements of the sensor is serially read.
The time-serially detected or serially read data is stored in a memory device. For example, Jpn. Pat. Appln. KOKAI Publication No. 4-256085 adopts an arrangement, as shown in FIG. 30. In a barcode reading apparatus described in this reference, data read by a barcode detection unit 1 is stored in a data memory unit 2 using a first-in first-out (to be abbreviated as a FIFO hereinafter) memory, and a barcode data group is detected by a barcode recognition unit 3. The storage address of the barcode data group in the data memory unit 2 is stored in an address memory unit 4. In this case, since the data memory unit 2 comprises a FIFO memory, the address value corresponds to the number of clocks from a reset timing. A barcode decoding unit 5 reads out barcode data from the data memory unit 2 on the basis of the address stored in the address memory unit 4 and executes decoding processing.
A barcode reader using a line sensor can read a one-dimensional barcode symbol by scanning the line sensor. However, in order to read a two-dimensional barcode symbol, the scanning operation of the line sensor must be repeated while moving the line sensor or the barcode symbol in a direction perpendicular to the line sensor.
However, when the scanning operation of the line sensor is repeated while moving the line sensor or the barcode symbol in the direction perpendicular to the line sensor, if the moving speed is low or the scanning speed of the line sensor is high relative to the moving speed, data in an identical row is read a plurality of number of times, and is repetitively stored in the memory. Therefore, in this case, when read barcode information is to be decoded, unnecessary information is included, resulting in an increase in decoding time.